US Coast Guard and military attempting to board Russian 'Shadow Fleet' tanker Marinera - Reuters

The United States has seized an oil tanker, now known as the Marinera and registered under the Russian flag, after a week-long pursuit, Reuters has reported, citing US officials.

"The seizure, which could stoke tensions with Russia, came after the tanker, originally known as the Bella-1, slipped through a U.S. maritime 'blockade' of sanctioned tankers and rebuffed U.S. Coast Guard efforts to board it," the news agency said in a statement on Wednesday.

The operation is being carried out by the Coast Guard and the US military. According to the agency's sources, Russian warships, including a Russian submarine, were nearby during the operation.

Separately, the US Coast Guard has intercepted another tanker linked to Venezuela in Latin American waters, U.S. officials told Reuters, as the United States continues to impose a naval "blockade" of vessels from Venezuela that are subject to sanctions.

Earlier in the day, Russia reportedly sent a submarine and other warships to protect an empty oil tanker trying to evade the U.S. Coast Guard in the Atlantic Ocean. The tanker has been trying to evade a blockade of sanctioned oil tankers near Venezuela for more than two weeks. The vessel has not docked in Venezuela or loaded oil. Although the vessel is empty, the U.S. Coast Guard has been pursuing the vessel in the Atlantic Ocean as part of a broader campaign to identify and seize a "shadow fleet" that transports illegal oil around the world, including oil from the Russian black market.

According to media reports, three US officials confirmed that Russia had asked the US to stop pursuing the vessel. The Russian Foreign Ministry said through state media that it was monitoring the situation "with concern."